Integrated coupling of scintillation crystal with photomultiplier in a detector apparatus

ABSTRACT

A scintillator type radiation detector package is provided including a scintillation crystal directly coupled to the window of a photomultiplier. A scintillator package is also provided having a longer life at wellbore temperature with minimal deterioration of a hygroscopic scintillation crystal(s). Direct optical coupling of the scintillator to the photomultiplier reduces the amount of light lost at coupling interfaces and improved detection resolution over the conventional structures having separate packages for crystal and photomultiplier.

BACKGROUND

Conventional radiation (e.g., gamma-ray) detectors for wellboreformation measurement (“well logging”) typically include a packagedphotomultiplier (“PMT”) and scintillation crystal. The most commonscintillation crystal is thallium-activated sodium iodide, NaI(Tl),which is a hygroscopic material and must be protected from moisture.Consequently, such NaI(Tl) crystals are typically packaged in ahermetically sealed container having an optical window to allow light toescape. The crystal is optically coupled to the interior surface of anoptically transparent window in the container, typically with a clearsilicone elastomer. This packaging method increases the number ofoptical interfaces, which causes a loss of light and detectorresolution. Some concepts to improve the optical efficiency of theforegoing crystal packaging including, e.g., the development claimed inU.S. Pat. No. 7,321,123 (Simonetti et al.) incorporated herein byreference and also owned by the assignee of the present invention. Inthe approach of this patent, the scintillator crystal replaces anoptical faceplate in the container and the photocathode of the PMT isdirectly deposited on the scintillator.

To construct a gamma-ray detector, in the typical detector, the exteriorsurface of the crystal container window is coupled optically to anexterior window of the photomultiplier (PMT), again using a clearsilicone elastomer. For light generated within the scintillation crystalto reach the photocathode of the photomultiplier (PMT), it must passthrough five interfaces: two on the optical coupling betweenscintillator and the scintillation crystal container window, two on theoptical coupling between crystal container window and the PMT window,and one between the PMT window and the photocathode of the PMT. At eachinterface, only a fraction of the light is transmitted, while reflectedlight may be eventually re-reflected back toward the interface or it maybe absorbed within the various optical media and thereby lost. It isadvantageous to reduce the number of optical interfaces between thescintillation crystal and the photocathode of the PMT as this willreduce the amount of reflected light and therefore increase the amountof light that reaches the photocathode. Increasing the amount of lightreaching the photocathode will improve the gamma-ray resolution andincrease the signal-to-noise ratio as long as other parameters, such asphotocathode quantum efficiency, are equal.

St. Gobain, a supplier of scintillator crystals, has published brochuresdescribing “integrated” detectors in which an entire photomultiplier andscintillator are packaged together in a common hermetically sealedhousing. Similar “integrated detectors” are also sold by GE-ReuterStokes. Such a system also has only three optical interfaces asdescribed above. However, the foregoing identified systems each hasdeficiencies with respect to shock-induced noise. This type of noisetypically is produced by flexing of the optical coupling orscintillation crystal with the resultant emission of light as a resultof the mechanical stress applied to the scintillator crystal. In the St.Gobain scintillation detector structure, the mass of the scintillationcrystal and the mass of the PMT are disposed on either side of anoptical coupling, and a shock, whether axial or lateral, will generateslight movement of the crystal and the PMT with respect to each other,and emit shock-induced light in the process. An additional disadvantageof the foregoing structure, in particular for LWD/MWD applications, isthat the PMT needs to be surrounded by shock absorbing materials insidethe housing. Outgassing of the shock absorbing material can damage thereflector, the optical coupling and can lead to an early failure of thePMT. For some very reactive scintillator material reactions withoutgassing products may tarnish the scintillator surface and degrade thescintillator performance.

SUMMARY

One aspect of the invention is a scintillator package including means tocouple a scintillation crystal directly to the window of aphotomultiplier (PMT). In the present aspect of the invention ascintillator package has a longer life at wellbore temperature withminimal, if any, deterioration of a hygroscopic scintillationcrystal(s). Direct coupling of the crystal to the PMT can reduce theamount of light lost at coupling interfaces and can improve gamma-rayresolution over a conventional structure having separate packages forthe crystal and photomultiplier. Also, the reduced light attenuationallows operation with higher thermal (dark) emission and thereforeallows operation at higher temperatures than conventional packaging. Inaddition, the coupling structure according to this aspect of theinvention can provide enhanced resistance to shock-induced noise that iscommon in operation of such devices in a wellbore drilled throughsubsurface formations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a possible construction of a PMT with weld flange to attacha crystal housing.

FIG. 2: shows a weld flange of the embodiment shown in FIG. 1

FIG. 3 shows integration of a ceramic PMT with a scintillator coupleddirectly to the faceplate.

FIG. 4 shows a PMT with a glass faceplate.

FIG. 5 shows a sealed integrated detector package known in the art.

FIG. 6 shows a modified glass tube with integrated package according toone example of the invention.

FIG. 7 shows insulated mounting of the detector housing according to oneexample of the invention.

FIG. 8 shows an example of mounting inside an extended faceplatesupport.

FIG. 9 shows an alternative embodiment with a prefabricated part withmachined groove between weld flange and window to assure minimaltemperature rise at the photocathode.

FIG. 10 shows a prefabricated PMT head according to FIG. 9.

FIG. 11 shows an example of mounting of the scintillator without acrystal.

FIG. 12 shows an example PMT head with a ‘shallow’ crystal housingbrazed to a window (KOVAR material and/or sapphire), closing window notshown.

FIG. 13 shows a PMT on the right with the crystal housing on left. TheKOVAR material head of the PMT and the crystal housing are both brazedto the same sapphire window.

FIG. 14a shows a PMT on right with sapphire window and crystal housingon left with sapphire window. The surface of the crystal window ischarged positively and the PMT window is charged negatively.

FIG. 14b shows when placed together, electrostatic forces join the twowindows tightly together, forming an optical medium through which lightfrom the scintillator can pass with little in the way of reflectionsfrom the joint.

FIG. 15 shows a PMT on the right with a sapphire window and a crystalhousing attached to a KOVAR material window flange. The surface of thecrystal is charged positively and the PMT window is charged negatively.When placed together, electrostatic forces join the crystal and windowtightly together, allowing light to pass directly into the windowwithout an optical coupling.

DETAILED DESCRIPTION

In one example of the present invention, the number of opticalinterfaces is reduced from five to three: two interfaces are provided onthe optical coupling between the scintillation crystal and the PMTwindow, and one interface is provided between the PMT window and thephotocathode of the PMT. This differs from a device known as the“scintiplier”, as described in U.S. Pat. No. 7,321,123, which has onlyone interface between the crystal and photocathode. However, in thedetector disclosed in the '123 patent, there are very few materials thatcan function as both scintillation crystal and PMT window, whereas inthe present invention, any know scintillation detector material can beused.

In the present invention, the scintillation crystal may be contained ina package that connects directly to the PMT window flange. Thiseffectively decouples the PMT mass from the optical coupling pad andreduces the potential of shock induced noise. In addition, the PMT ofthe current invention has an extremely rugged sapphire/metal/ceramicstructure, so the crystal can be loaded with high compressive forcewithin the crystal housing, greatly reducing any crystal movement thatwould produce shock-induced counts. Such a high compressive force wouldbreak a glass PMT envelope of the previous integrated designs.

One example of the present invention includes a photomultiplier (“PMT”)having a sapphire optical window and a metal and ceramic brazed housing(see FIG. 1). The sapphire window (faceplate) is brazed to a cylindricalflange that is, in turn, welded onto a faceplate weld flange. Across-sectional view of an example embodiment of this flange is shown inFIG. 2. In one method of enclosing the scintillation crystal, acylindrical housing is welded onto the integration flange, FIG. 3, belowthe PMT head. The scintillation crystal and its optical coupling areloaded through the open end of the housing and sealed with an end cap.Typically, the end cap contains a spring to apply compressive force tothe scintillation crystal, and the threaded housing provides a mechanismto apply the compressive force. Additionally, optically reflectivematerial such as one sold under the trademark TEFLON®, which is aregistered trademark of E.I. du Pont De Nemours & Co., Wilmington, Del.,may be disposed in a gap between the scintillation crystal and thehousing to reflect light back toward the photomultiplier and to providea shock absorptive mount for the crystal. Finally, the end of the endcap may be welded to the end of the housing to form a hermetic seal.Typically, the entire crystal loading procedure is performed in an inertgas atmosphere, such as argon, to prevent deterioration of hygroscopicscintillation crystals. Hygroscopic crystal compositions may include,for example, NaI(Tl), LaBr₃:Ce, LaCl₃:Ce, CsI(Na), CsI(Tl), mixedLa-halides, elpasolites (such as CLYC etc), SrI₂:Eu and others known inthe art.

The crystal/PMT package of the present invention is not limited to useof only hygroscopic scintillator crystals. The same package and mountingmethod can be used for non-hygroscopic scintillator crystals. Useful nonhygroscopic crystals may include BGO, LSO:Ce, GSO:CE, YAP:Ce, YAP:Pr,LuAP:Ce, LuAG:Pr, as well as others known in the art, for example Li⁶doped glass. When such types of crystals are used, a hermetic seal maynot be required. However hermetic sealing even in the case ofnon-hygroscopic crystals may reduce premature deterioration of thereflector material in particular when the packages are exposed to hightemperatures.

Welding the end cap, while being one preferred method, is not the onlyapproach to form a seal. It is also possible to use other sealingtechniques using adhesives, low temperature solder, O-ring seals orsimilar techniques known in the art. In some cases, the joining andsealing technique may include cold welds or the use of metal seals.

Other example implementations are also possible. In an alternateexample, FIG. 4 shows a PMT with a glass window instead of a sapphirewindow but, otherwise, the arrangement is similar to that describedpreviously.

The examples disclosed in the previous paragraphs include one structurefor integrating a scintillation crystal in a hermetically sealedenvironment directly optically coupled to a PMT. The structure of thePMT lends itself for this kind of integration. However, in analternative example, a glass PMT may be used, albeit of a more complexconstruction. As mentioned above, present integrated detectors based onglass PMTs enclose the entire glass envelope in an hermetic enclosure.This type of construction is outlined in FIG. 5. In addition to theissues mentioned above, such a construction puts the entire PMT incompression and the enclosure will typically include potting materialthat could outgas at higher temperatures and possibly damage thescintillator and/or photomultiplier.

In another example, the construction of the glass envelope could bemodified by adding an intermediate metal ring to the envelope, whichwould serve as a surface for attaching a scintillator housing. Anoutline of such an approach is shown in FIG. 6. Instead of using anintermediate metal ring that bisects the envelope, the metal ring couldalso be simply resting in a groove on the outside of the envelope,leaving the inside of the glass envelope intact. The ring would thus behermetically sealed to the glass envelope.

Two embodiments of methods of assembly will be described; however, theseare examples only, and the scope of the invention is not limited tothese two example methods. In one method, an open metal can is attachedto the metal ring on the PMT by means of welding, chemical adhesion,soldering or other appropriate attachment methods before the processing(application of the photocathode) of the PMT. The optical coupling andscintillator may be installed and the end cap may be attached andhermetically sealed by an appropriate sealing method on the finishedPMT.

In a second alternative example, the scintillator, optical coupling,etc. may be installed on the PMT faceplate and then a cylinder with aclosed end is fit over the assembly and welded or otherwise attached tothe metal ring on the processed PMT. The latter method may have theadvantage of being a simpler assembly, but sealing techniques such aswelding may elevate the temperature close to the photocathode and mayincrease the possibility of damage to the photocathode. The foregoingassembly methods mentioned herein apply equally to ceramic and glass PMTconstructions.

An alternative approach to the method mentioned above is to install thescintillator crystal with its reflector, shock absorber and compressionspring in a cylindrical housing before assembling it with the PMT. Ineither case, a possible advantage of such construction is theaccessibility of the PMT optical window. This allows improved cleaningand preparation of the optical window surface before assembly. Properheat sinking should to be used during assembly to ensure that thephotocathode does not get damaged during welding.

In many applications, including well logging, the PMT can be run withnegative high voltage (HV), i.e., the photocathode is operated at anegative high voltage, while the anode is kept at ground potential. Thisallows DC coupling of the anode output to the following preamplifier andanalysis circuitry. The present invention can be used in the foregoingconfiguration. However, the entire detector housing would be at negativeHV (up to about 2000 V) in such a configuration. This requires properinsulation and precautions in the construction to avoid HV leakage fromthe cathode. On the other hand the approach eliminates issues that maybe experienced due to the very high field stresses in previously knownassemblies where ground potential and cathode high voltage are veryclose together.

The foregoing disadvantages could be alleviated by attaching thescintillator housing to an insulator, such as a ceramic ring. Onepossible approach is shown in FIG. 7. The detector housing is mounted onan extended ceramic ring (or other insulating structure that can behermetically sealed). This makes it possible to keep the detectorhousing at ground potential. Sufficient insulation needs to be providedto make sure that there are no leakage currents between the photocathodeand ground. This approach has the same issues as previously knowndetectors that operate at negative high voltage. As in this constructionthere is a possibility that the electric field at least at the edge ofthe photocathode is affected by the presence of the high voltage nearbyand this may affect the quantum efficiency of the device and/or the darkcurrent. This problem could be alleviated by extending the mountingcylinder of the faceplate beyond the faceplate as shown in FIG. 7

In yet another example, the support for the faceplate and the containerfor the scintillator could be the same structure. One such exampleembodiment is shown in FIG. 8. In all such embodiments, a weldedendplate is shown. Other embodiments for this structure are equallypossible, including but not limited to welding a half cylinder with theendplate already attached to an open half cylinder, thereby moving theweld to a location intermediate between the bottom and the top of thecan. Generally, welding very close to the faceplate should be avoidedafter the photocathode has been deposited.

In many cases, metal-ceramic PMTs are constructed of Alumina ceramic andnickel ferrous alloys. One example of such an alloy is a nickel-cobaltferrous known as KOVAR® which is a registered trademark of CarpenterTechnology Corp., or the like, because of the closely matchedcoefficients of thermal expansion. The weld flange would typically beattached to the KOVAR® material rings through brazing or welding. Thematerial of the scintillator housing can be any material suitable tocontain a scintillator. Typical materials include stainless steel,titanium and aluminum using suitable joining techniques. The selectioncould also include ceramic materials or plastics using suitable sealingtechniques. In some embodiments, where a direct joint between twomaterials is not possible, an intermediate material component may beused to join the two.

FIG. 9 shows a PMT with a head with a machined weld flange. This avoidsa weld process, on the thin material of the head, which could cause achange in dimensions and/or weaken the material. A groove is machinedbetween the place where the sapphire is attached and the weld lip toprevent excessive heating of the photocathode during the weld process.The thick material below the limit serves as a heat sink and can also beprovided with a thread so that the PMT housing can be threaded onproviding a very stable mechanical connection and enhanced shockresistance. A prefabricated PMT head is shown in FIG. 10.

FIG. 11 shows an example which may be particularly suited for smallerand/or lighter scintillation crystals. Such scintillators can bedirectly attached to the faceplate using an optical coupling agent(transparent adhesive, silicone etc). The bond obtained with thistechnique is strong enough to hold the scintillator in place even in theabsence of a retaining spring. The elimination of the spring componentbrings the front face of the scintillator closer to the end of thehousing and reduces the amount of material between the scintillator anda radiation source. This enhances the detection probability,particularly for lower energy radiation. A single weld may be sufficientto attach the cap over the scintillator. In addition, the end cap can beslightly bent inward to provide a small amount of retaining force on thescintillator.

FIG. 12 shows an example which seals the scintillator housing againstthe faceplate of a PMT. Operating at negative HV does not require aninsulating layer, allowing for a smaller diameter detector. Combinationcrystal mountings, as shown in FIG. 11, and housings, as shown in FIG.12, having very thin entrance windows brazed to the crystal housing,were built to be used as as low energy, high temperature x-raydetectors.

FIG. 13 shows an embodiment in which the scintillator housing is brazedto the same sapphire window as the KOVAR® material window supportcylinder of the PMT. The scintillator housing may be likewiseconstructed of KOVAR® material so as to match the expansion coefficientof the sapphire, but other metals can also be used.

FIG. 14 shows an embodiment similar to that of FIG. 13, that both thecrystal housing and the PMT have a sapphire window and the two windowsare joined tightly together electrostatically. Prior to joining, onesurface is charged negatively and the other is charged positively.Various methods of charging are available but one preferred method is tocharge one of the surfaces by Al⁺ implantation and to charge the othersurface by O⁻ implantation. These components are chosen because they arethe same elements of which the sapphire is composed, forming a verystrong bond when the two surfaces are joined. For this method tosucceed, the surfaces need to be extremely flat (<<½λ, where λ is thewavelength of the incident light) and polished. This may requirere-polishing the surface of the PMT window after the deposition of thephotocathode.

FIG. 15 shows an example in which the crystal surface and window surfaceare charged to opposite polarities so that the electrostatic forcesdirectly join the two surfaces, without requiring an optical couplingpad or grease. This eliminates one optical interface and one material(the coupling pad or grease) which generally causes an index ofrefraction mismatch to both the scintillator and the PMT window. As aresult, this embodiment is much more efficient at transmitting lightfrom the scintillator to the PMT cathode.

Another way to obtain a tight bond between the two surfaces is thermalbonding, shown in FIG. 15. This involves coupling between the crystalsurface and window surface by optical contact of the precision-polishedcrystal and PMT window surfaces and subsequent thermal treatment toincrease the bond strength. In this case Van-der-Waals intermolecularforces will act as attractive forces to couple the components.

In yet another embodiment, a bond between a sapphire faceplate and ascintillation crystal can be achieved if both materials contain elementsthat make it possible to produce an interface layer on the surface ofeither of: the faceplate, the scintillator or both, to obtain a tightbond when joining the surfaces. This can be achieved with Al-Perovskiteof the form ABO₃, where B denotes Aluminum and A can be any othersuitable element like Lu or Y, or other rare earth element and joiningit to sapphire (Al₂O₃). One example would be joining LuAP to a sapphireface plate. This can be achieved by implanting (e.g. ion implantation) asmall amount of Lu in the surface of the sapphire. Such implantationcreates a shallow lattice distortion approaching the ABO₃ Perovskitestructure to obtain a solid bond between the sapphire and thescintillator. The same approach can be used with YAP scintillators, e.g.YAP:Ce, YAP:Pr, and the like, or mixed Lu—Y scintillators (LuYAP) byimplanting Y and/or Lu. The application is not limited to perovskites.Al-garnet (e.g. LuAG, LuYAG, YAG) can be bonded to sapphire. In somecases, this may require surface modifications on one or both of thefaceplate and the scintillator.

The approach described above can also be used to bond a silicatescintillator (e.g. GSO, YSO, LSO, LYSO, LPS) to a Quartz (SiO₂) window.This can be achieved by implanting Gd ions (for GSO) in the surface ofthe quartz window to obtain a shallow lattice distortion to allow adirect bond between Quartz and the scintillator. Quartz is used in PMTsthat require windows that are transparent to far UV photons (wavelengthλ<200 nm).

If magnetic shielding is required, the scintillator housing could beformed directly of a high permeability ferromagnetic material. One suchmaterial is available as “ADMU-80”, from Advanced Magnetics. Thescintillator can also be surrounded by such a material.

Certain methods to reduce unwanted shock or vibration-induced countsinclude placing a conductive coating on the optical pad. See, forexample, US Patent Application Publications 2009/0278052, and US2011/0001054. Another technique, e.g., as shown in U.S. Pat. No.7,675,040 introduces gases within the crystal housing that inhibitcharge movement (e.g., SF₆). The above mentioned development is onlyconcerned with filling the inside of a hermetically sealed scintillatorpackage. However, shock and vibration induced counts are generated notonly at the location of the optical coupling inside the detectorhousing. It is equally possible that such counts are caused at theinterface between the packaged scintillator and the photomultiplier. Toreduce this problem, the scintillator package and the PMT or at leastthe PMT faceplate and the adjacent optical coupling can be housed in ahermetically sealed enclosure, which is filled with a gas that impedesthe movement of charges. In this way, shock or vibration induced countsdue to charging of the previously mentioned optical coupling pad may bereduced or eliminated. In the case of the the previously disclosures, itis an embodiment that in any of the housing configurations discussedherein where the scintillation crystal is coupled to the PMT window bymeans of an optical interface device (e.g., an optical coupling pad), athin (optically transparent) conductive coating may be applied to thesurface of the PMT window to reduce or prevent discharges and thereforeshock or vibration induced counts.

Also, a thin (optically transparent) conductive coating may be appliedto the scintillation crystal (either to the face that is in contact withthe optical coupling pad or to all faces of the crystal), also toprevent discharges. In the case of those housing configurations wherethe crystal is coupled directly to the PMT window without an opticalcoupling pad, the surfaces of the crystal not in contact with thewindows may be coated with a thin (optically transparent) conductivecoating to prevent electrical discharges along the crystal. Such anoptical coupling can be obtained either by the deposition of a thin(transparent) metallic film or by surface modification (e.g.implantation of a material like Ti in the sapphire window).

Alternately or additionally, the reflective material in contact with thescintillation crystal may be coated with a thin (optically transparent)conductive coating to prevent electrical discharges. It is also anembodiment that, for the conventional geometries, shock or vibrationinduced counts due to discharges at the optical coupling pad may bereduced or eliminated by application of a thin (optically transparent)conductive coating to the PMT window and/or crystal housing window.Methods of applying a thin conductive layer to materials, includingevaporation, sputtering or chemical vapor deposition (CVD), are wellknown in the art. Alternately, the reflective material could be a highlyoptically reflective metal foil such as Ag, Al or Ti. Since the surfacesof such metals may tarnish if exposed to air, enclosing them in ahermetically sealed container would prevent such deterioration.

U.S. Pat. Nos. 7,884,316, 5,869,836, and U.S. Patent ApplicationPublication No. 2010/0193690 disclose methods of placing a shockabsorbing boot around the scintillation crystal of a scintillationdetector, either as a single piece boot or as boot segments spacedlongitudinally along the crystal. U.S. Pat. No. 6,222,192 also disclosesplacing a boot along the entire length of crystal and PMT. In oneexample of the present invention a shock absorbing boot may be placedaround the entire length of the scintillation crystal but may alsoextend to the point where the crystal housing is attached to the PMT(which is less than the length of the PMT). The boot may be formed of asingle piece or it may be segmented along the length.

While the invention has been disclosed with reference to a limitednumber of example implementations, those skilled in the art, having thebenefit of this disclosure will readily devise other implementationswhich do not exceed the scope of what has been invented. Accordingly,the invention shall be limited in scope only by the attached claims.

1-27. (canceled)
 28. An integrated scintillation detector comprising: ascintillation crystal and a photomultiplier having a faceplate, saidphotomultiplier being at least partially contained within a scintillatorhousing, wherein the scintillator crystal is directly attached to thephotomultiplier faceplate without an optical coupling pad.
 29. Theintegrated scintillation detector of claim 28 wherein the scintillatorhousing is hermetically sealed.
 30. The integrated scintillationdetector of claim 28 wherein the scintillator crystal is hygroscopic.31. The integrated scintillation detector of claim 30 wherein thescintillator crystal is a material selected from the group consisting ofNaI(Tl), LaBr₃:Ce, LaCl₃:Ce, CsI(Na), CsI(Tl), mixed La-halides,elpasolites, and SrI₂:Eu.
 32. The integrated scintillation detector ofclaim 28 wherein the scintillator crystal is non-hygroscopic.
 33. Theintegrated scintillation detector of claim 32 wherein the scintillatoris formed from a material selected from the group consisting of BGO,LSO:Ce, GSO:CE, YAP:Ce, YAP:Pr, LuAP:Ce, and LuAG:Pr.
 34. The integratedscintillation detector of claim 28, wherein the photomultiplier has ahead, the head having a weld flange and wherein the scintillator housingis attached to the weld flange at an end of the photomultiplier head.35. The integrated scintillation detector of claim 28, wherein thescintillator housing is attached to a structure selected from a metalstructure and a ceramic structure positioned at a distance from thephotomultiplier.
 36. The integrated scintillation detector of claim 28,wherein a cylinder supports both the faceplate and the scintillatorhousing.
 37. The integrated scintillation detector of claim 28, whereinthe photomultiplier comprises a glass envelope incorporating a supportfor attachment of the scintillator housing wherein less than the entirephotomultiplier is enclosed in the scintillator housing.
 38. Theintegrated scintillation detector of claim 37, wherein the support is ametal ring or disk included in the glass envelope.
 39. The integratedscintillation detector of claim 28 where the scintillator housing isbrazed to the faceplate of the photomultiplier window at a top or a sideof the faceplate.
 40. The integrated scintillation detector of claim 28,wherein the scintillator housing has an endplate, the endplate beingbent inward to apply a force to the scintillator crystal, pushing itagainst the faceplate of the photomultiplier.
 41. The integratedscintillation detector of claim 28, wherein the direct attaching isachieved through opposite electrostatic charges on surfaces that arejoined.
 42. The integrated scintillation detector of claim 41, whereinthe direct attaching between surfaces being coupled is followed by aheat treatment to solidify a bond therebetween.
 43. The integratedscintillation detector of claim 28, wherein the scintillator crystal isdirectly affixed to the face plate by means of a bonding layer placedeither on the face plate, the scintillator or both before joiningthereof.
 44. The integrated scintillation detector of claim 43 whereinthe scintillator crystal comprises an aluminum perovskite of the formABO₃, where B is aluminum and A is an element selected from the groupconsisting of Lu, Y and other rare earth elements and wherein the faceplate is sapphire and a bonding layer is created by implanting element Ain the sapphire to distort a crystalline lattice to form a thinconnecting perovskite layer.
 45. The integrated scintillation detectorof claim 28, wherein the photomultiplier comprises a photocathode, thephotocathode being deposited before attaching the scintillator housingto the photomultiplier.
 46. The integrated scintillation detector ofclaim 1, wherein the photomultiplier comprises a photocathode, thephotocathode being deposited after attaching the scintillator housing tothe photomultiplier.
 47. The integrated scintillation detector of claim1 wherein at least one feature selected from the window of thescintillator housing, the scintillation crystal and the faceplate of thephotomultiplier is formed from a material selected from the groupconsist of stainless steel, nickel ferrous alloys, titanium, aluminum,plastic and ceramic.